JP2003089718A - Epoxy resin composition and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an epoxy resin composition for semiconductor sealing use having good moldability, high flame retardancy even if using no flame retardant, and high soldering crack resistance. SOLUTION: The epoxy resin composition for semiconductor sealing use essentially comprises (A) a phenolaralkyl-type epoxy resin with diphenylene skeleton, (B) a phenolaralkyl resin with diphenylene skeleton, (C) 80-90 wt.% of an inorganic filler, and (D) a phosphorus-containing curing promoter of the formula [wherein, R1 to R4 are each a substituent selected from monovalent aromatic ring-containing organic groups and monovalent aliphatic residues; and an organic acid: Y<n-> [H<+> ]n-m represents an organic anion resulted from releasing (m) protons out of the molecule, wherein n>=m>=1], wherein the phosphorus content of the resin composition attributable to the above curing promoter is 0.015-0.05 wt.%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an epoxy resin composition for semiconductor encapsulation, which is excellent in moldability, and a semiconductor device.

[0002]

2. Description of the Related Art Conventionally, electronic parts such as diodes, transistors and integrated circuits have been sealed mainly with an epoxy resin composition. Especially in integrated circuits, epoxy resin,
An epoxy resin composition having excellent heat resistance and moisture resistance, which is a mixture of a phenol resin and an inorganic filler such as fused silica or crystalline silica, is used. In recent years, in the market trend of miniaturization, weight reduction, and high performance of electronic devices, semiconductor elements have been highly integrated, and surface mounting of semiconductor devices has been promoted. The demands on the existing epoxy resin compositions are becoming more and more stringent.
In particular, as part of the elimination of environmentally hazardous substances, replacement with lead-free solder is being promoted.

Conventional leaded solder has a melting point of 183 ° C. and a solder reflow temperature of 220 to 240 ° C. during mounting.
Since the lead-free solder has a high melting point, the solder reflow temperature at the time of mounting is higher by about 20 ° C. than before, and 260 ° C. is required. The problem of cracking of the semiconductor device due to peeling at the interface between the cured product of the epoxy resin composition and the pad and peeling at the interface between the semiconductor element and the semiconductor resin paste due to the change in the solder reflow temperature for handling lead-free solder Has occurred. These solder cracks and peeling are considered to be caused by water absorption by the semiconductor device itself before the solder reflow treatment, and the water content causing a steam explosion at high temperature during solder reflow, and an epoxy resin composition for preventing it. Is often used, and as one of the methods for reducing the water content, an epoxy resin represented by the general formula (1) and a phenol resin represented by the general formula (2) having a low water absorption property are used. It has been proposed to reduce the water absorption of a cured product of an epoxy resin composition by using.

In addition, usually, in order to impart sufficient flame retardancy to the epoxy resin composition, an bromine-containing organic compound and an antimony compound such as antimony trioxide or antimony tetroxide are often mixed. However, in recent years, there has been a movement to reduce or eliminate substances that may be harmful due to the emphasis on corporate activities that consider the global environment, and epoxy resins with excellent flame retardancy without using bromine-containing organic compounds and antimony compounds. The development of compositions is required. As an environmentally friendly flame retardant alternative to these, aluminum hydroxide,
Epoxy resin compositions containing metal hydroxides such as magnesium hydroxide and red phosphorus have been proposed, and semiconductor devices using the epoxy resin compositions containing these flame retardants are UL-94 vertical in flame retardancy test. Test (test piece thickness 3.2 mm, 1.
6 mm), V-0 is achieved, but moldability and curability are deteriorated, and solder crack resistance during surface mounting may be deteriorated. Further, there is a problem that the moisture resistance reliability and the high temperature storability are lowered, and an epoxy resin composition which is sufficiently satisfied cannot be obtained. When the epoxy resin represented by the general formula (1) and the phenol resin represented by the general formula (2) are combined and the flame retardant is not used, the flame retardancy is UL-94 vertical test (test piece thickness). 3.2 mm), V-0 can be achieved, but V-0 cannot be achieved with a test piece thickness of 1.6 mm considering recent surface mounting semiconductor devices, and it is possible to meet all requirements. could not.

[0005]

DISCLOSURE OF THE INVENTION The present invention provides a semiconductor device excellent in flame retardancy and excellent in solder crack resistance even if it does not contain a semiconductor encapsulating epoxy resin composition having excellent moldability and a flame retardant. It is provided.

[0006]

The present invention provides [1] (A) an epoxy resin represented by the general formula (1),
(B) Phenolic resin represented by the general formula (2), (C)
An inorganic filler and (D) a curing accelerator containing phosphorus represented by the general formula (3) as essential components, and the inorganic filler in the total epoxy resin composition is 80 to 90% by weight, and the total epoxy resin composition An epoxy resin composition for semiconductor encapsulation, wherein the phosphorus content due to the curing accelerator containing phosphorus is 0.015 to 0.05% by weight,

[0007]

[Chemical 4] (In the formula, R ₁ and R ₂ are groups selected from alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is An integer of 0 to 4, and n is a positive number of 1 to 5 on average.

[0008]

[Chemical 5] (In the formula, R ₁ and R ₂ are groups selected from alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is An integer of 0 to 4, and n is a positive number of 1 to 5 on average.

[0009]

[Chemical 6] (In the formula, R _{1 to} R ₄ each represent a substituent selected from the group consisting of a monovalent aromatic ring-containing organic group and a monovalent aliphatic residue, and may be the same or different. Well, the organic acid Y ^n- [H ⁺ ] _nm represents an organic anion that releases m protons out of the molecule, n ≧ m ≧ 1).

[2] A semiconductor device comprising a semiconductor element encapsulated with the epoxy resin composition as described in the item [1].

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION General formula (1) used in the present invention
The epoxy resin represented by has a diphenylene skeleton that is hydrophobic and rigid between epoxy groups, and the heat resistance is less reduced despite the low crosslink density, and a cured product of an epoxy resin composition using this is It has a low water absorption rate, a low elastic modulus in a high temperature range exceeding the glass transition temperature, and is excellent in adhesion to a semiconductor element or a lead frame. Therefore, the semiconductor device sealed with the epoxy resin composition using this epoxy resin,
High reliability can be obtained even under solder reflow during mounting.

In the general formula (1), n is an average value, preferably a positive number of 1 to 5, and particularly preferably 1 to 3. n = 1
If it is less than the above range, the curability of the epoxy resin composition is deteriorated, which is not preferable. When n = 5 is exceeded, the resin viscosity increases and the fluidity of the epoxy resin composition decreases, which is not preferable.
By adjusting the amount of the epoxy resin represented by the general formula (1) to be used, the solder crack resistance can be maximized. In order to bring out the effect of resistance to solder cracking, it is desirable that the epoxy resin represented by the general formula (1) is contained in an amount of 50% by weight or more, more preferably 70% by weight or more, based on the whole epoxy resin. If it is less than 50% by weight, the cured product may be easily burned, the water absorption may be increased, or the elastic modulus may be increased, so that the solder crack resistance may be deteriorated.

When used in combination with the epoxy resin represented by the general formula (1), the epoxy resin includes all monomers, oligomers and polymers having an epoxy group in the molecule,
For example, phenol novolac type epoxy resin, ortho-cresol novolac type epoxy resin, cresol novolac type epoxy resin, biphenyl type epoxy resin, bisphenol type epoxy resin, stilbene type epoxy resin, triphenol methane type epoxy resin, naphthol type epoxy resin, naphthalene type epoxy resin. Examples thereof include resins, alkyl modified triphenol methane type epoxy resins, triazine nucleus-containing epoxy resins, dicyclopentadiene modified phenol type epoxy resins and the like. If another epoxy resin is used in combination, the moldability may be poor, and the moldability can be improved by using the curing accelerator of the present invention described later.

The phenol resin represented by the general formula (2) used in the present invention has a hydrophobic and rigid diphenylene skeleton between phenolic hydroxyl groups, and a cured product of an epoxy resin composition using this is It has a low water absorption rate, a low elastic modulus in a high temperature range exceeding the glass transition temperature, and is excellent in adhesion to a semiconductor element or a lead frame. Further, it has a feature that it has high heat resistance despite its low crosslink density. Therefore,
The semiconductor device sealed with the epoxy resin composition using the phenol resin can obtain high reliability even during solder reflow during mounting.

In the general formula (2), n is an average value, preferably a positive number of 1 to 5, and particularly preferably 1 to 3. n = 1
If it is less than the above range, the curability of the epoxy resin composition is deteriorated, which is not preferable. When n = 5 is exceeded, the resin viscosity also increases and the fluidity of the epoxy resin composition decreases, which is not preferable.
By adjusting the amount of the phenol resin shown by the general formula (2) to be used, solder crack resistance can be maximized. In order to bring out the effect of the solder crack resistance, it is desirable that the phenol resin represented by the general formula (2) is contained in an amount of 50% by weight or more, more preferably 70% by weight or more, based on the total phenol resin. If it is less than 50% by weight, it is easy to burn, the water absorption is high, the elastic modulus is high, and the solder crack resistance may be lowered.

When used in combination with the phenol resin represented by the general formula (2), it can be used for all monomers, oligomers and polymers having a phenolic hydroxyl group in the molecule, such as phenol novolac resin, cresol novolac resin, naphthol aralkyl resin, triphenol. Examples thereof include methane resin, terpene modified phenol resin, dicyclopentadiene modified phenol resin and the like. The equivalent ratio [(the number of epoxy groups) / (the number of phenolic hydroxyl groups)] of the number of epoxy groups of all epoxy resins and the number of phenolic hydroxyl groups of all phenolic resins used in the present invention is preferably 0.5 to 2, and particularly 0. 0.7 to 1.5 is desirable. When it is out of the range of 0.5 to 2, the curability of the epoxy resin composition is lowered, the glass transition temperature of the cured product is lowered, the humidity resistance is lowered, and the like, which is not preferable.

The type of the inorganic filler used in the present invention is not particularly limited, for example, fused silica, spherical silica, crystalline silica, secondary agglomerated silica, porous silica, secondary agglomerated silica or silica obtained by pulverizing porous silica. , Alumina, titanium white, aluminum hydroxide, silicon nitride, etc., the shape of the inorganic filler may be a crushed shape or a spherical shape, but in order to improve solder crack resistance, a high filling point or a flow Spherical fused silica is preferred from the viewpoint of the balance of the properties, mechanical strength and thermal properties. The maximum particle size is preferably 75 μm or less, and the average particle size is preferably 5 to 25 μm. As for the particle size distribution, the particle size distribution is preferably broad in order to improve the fluidity and reduce the melt viscosity of the epoxy resin composition during molding.

The content of the inorganic filler is preferably 80 to 90% by weight in the total epoxy resin composition. 80% by weight
If the amount is less than this, low water absorption of the cured product of the epoxy resin composition cannot be obtained, and further, the strength at the solder reflow temperature decreases, resulting in insufficient solder crack resistance, and brominated orthocresol novolac type epoxy. Resins, bromine-containing bis-A type epoxy resins and other bromine-containing organic compounds and antimony compounds such as antimony trioxide and antimony tetroxide are not preferred because flame retardancy is insufficient unless flame retardants are added. 90
If the content exceeds 10% by weight, the fluidity of the epoxy resin composition will decrease, filling defects and pad shifts of semiconductor elements are likely to occur during molding, and there is a risk of inconvenience such as deformation of the gold wire in the semiconductor device due to high viscosity. It is not preferable because it exists. The inorganic filler should be blended as much as possible, so that the water absorption of the cured product of the epoxy resin composition can be reduced and the solder crack resistance is improved. Just adjust it.

The inorganic filler used in the present invention is preferably thoroughly mixed in advance, and if necessary, the inorganic filler may be previously treated with a silane coupling agent, an epoxy resin or a phenol resin. Examples of the method include a method of removing the solvent after mixing with a solvent and a method of directly adding to the inorganic filler and treating with a mixer.

The curing accelerator containing phosphorus represented by the general formula (3) used in the present invention is a molecular association product of a tetra-substituted phosphonium and an organic acid. It is considered that it is composed of a tetra-substituted phosphonium cation and an organic anion, and the positive charge of the tetra-substituted phosphonium ion is surrounded by the organic anion to have a stabilized structure. The phosphonium ion capable of having such a structure is preferably a tetra-substituted phosphonium ion having a substituted or unsubstituted aryl group or alkyl group as a substituent because it is stable against heat and hydrolysis, and specifically, tetraphenyl Examples thereof include tetraaryl-substituted phosphoniums such as phosphonium and tetratolylphosphonium; triarylmonoalkylphosphoniums synthesized from triarylphosphines and alkyl halides such as triphenylmethylphosphonium; and tetraalkyl-substituted phosphoniums such as tetrabutylphosphonium.

The organic acid which is the other component forming the molecular compound is bisphenol A (2,2- (4
-Hydroxyphenyl) propane, 4,4'-biphenyl, bisphenol F (4,4'-methylenebisphenol, 2,4'-methylenebisphenol, 2,2'-
Methylene bisphenol), bis (4-hydroxyphenyl) sulfone (bisphenol S), 3,3'-dimethylbisphenol S, bisphenol E (4,4'-
Ethylidene bisphenol), bisphenol fluorene (4,4 '-(9H-fluorene-9-ylidene) bisphenol), 4,4'-methylidene bis (2,6-
Dimethylphenol), bisphenols such as bis (4-hydroxyphenyl) methane, 4,4′-biphenol, 2,2′-biphenol, 3,3 ′, 5,5′-
Biphenols such as tetramethylbiphenol, 2,2-bis (4-hydroxyphenyl) 1,1,1-3,3,3-hexafluoropropane, hydroquinone, resorcinol, catechol, bis (4-hydroxyphenyl) ether, 2,6-dihydroxynaphthalene, 1,
4-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,1 '
-Bi-2-naphthol, 1,4-dihydroxyanthraquinone, 2,2'-di (oxobiphenyl) borate, etc. are exemplified, but in view of stability of the molecular compound, curability, and physical properties of the cured product, bisphenol A is used. , Bisphenol F
(Including 4,4'-methylenebisphenol, 2,4'-methylenebisphenol, 2,2'-methylenebisphenol and a mixture of these isomers such as bisphenol FD manufactured by Honshu Chemical Industry Co., Ltd.), bisphenol S ，
3,3'-Dimethylbisphenol S, 4,4'-biphenol, 2,2-bis (4-hydroxyphenyl)
1,1,1-3,3,3-hexafluoropropane, bis (4-hydroxyphenyl) ether, 2,3-dihydroxynaphthalene, 4,4′-biphenyl, 2,2 ′
-Di (oxobiphenyl) borate is preferred.

The content of the curing accelerator containing phosphorus is
0.1 to 1% by weight in the total epoxy resin composition is preferable,
If the amount is less than 0.1% by weight, the curing of the epoxy resin composition will not be sufficiently accelerated, and if the amount exceeds 1% by weight, the fluidity of the epoxy resin composition will decrease, which is not preferable. The phosphorus content due to the curing accelerator containing the phosphorus in the total epoxy resin composition,
In order to exhibit flame retardancy, 0.015 to 0.05% by weight is preferable. If it is less than 0.015% by weight, it is flame-retardant UL-94.
In a vertical test (test piece thickness: 1.6 mm), V-0 cannot be achieved and sufficient flame retardancy cannot be obtained. On the other hand, 0.05% by weight
If it exceeds the range, the fluidity of the epoxy resin composition decreases, which is not preferable.

The epoxy resin composition of the present invention does not contain a flame retardant such as a bromine-containing organic compound, an antimony compound and a metal hydroxide, and the UL-94 vertical test (test piece thickness 1.
6 mm), V-0 can be achieved. But,
It is difficult to reduce the amount of the flame retardant mixed in the raw material or the manufacturing stage to 0% by weight even if the flame retardant is not intentionally added. Therefore, even if the flame retardant is mixed in the order of ppm and ppb, Effects such as moldability and solder crack resistance are achieved.

The epoxy resin composition of the present invention comprises (A)-
In addition to the component (D), if necessary, an inorganic ion exchanger such as bismuth oxide hydrate, a coupling agent such as γ-glycidoxypropyltrimethoxysilane, a coloring agent such as carbon black and red iron oxide, a silicone oil, It is possible to add various additives such as a stress reducing component such as silicone rubber, a natural wax, a synthetic wax, a releasing agent such as higher fatty acids and their metal salts or paraffin, and an antioxidant. There is no problem even if it is used in combination with a catalyst such as 1,8-diazabicyclo (5,4,0) undecene-7 or 2-methylimidazole as long as the properties of the curing accelerator represented by the general formula (3) are not impaired. Absent.

The epoxy resin composition of the present invention comprises (A)-
It is obtained by mixing the component (D) and other additives at room temperature using a mixer or the like, heating and kneading with a kneader such as a roll, kneader or extruder, cooling and pulverizing. INDUSTRIAL APPLICABILITY The epoxy resin composition of the present invention can be applied to coating / insulating / sealing of transistors, integrated circuits, etc., which are electric or electronic parts. In order to manufacture a semiconductor device by sealing an electronic component such as a semiconductor element using the epoxy resin composition of the present invention, molding and curing may be performed by a molding method such as a transfer mold, a compression mold or an injection mold.

[0026]

The present invention will be described in detail below with reference to examples of the present invention, but the present invention is not limited thereto. The mixing ratio of each component is parts by weight. Example 1 Epoxy resin a represented by the formula (4) (softening point 60 ° C., epoxy equivalent 270, ICI melt viscosity at 150 ° C. 0.8 × 10 ² mPa · s,) 6.6 parts by weight

[0027]

[Chemical 7]

4.5 parts by weight of a phenolic resin c represented by the formula (5) (softening point: 65 ° C., hydroxyl group equivalent: 203, ICI melt viscosity at 150 ° C .: 1.0 × 10 ² mPa · s,)

[0029]

[Chemical 8]

[0030]   The curing accelerator e represented by the formula (6) (hydroxyl group equivalent: 185, phosphorus content: 4.2% by weight) %) 0.4 parts by weight

[0031]

[Chemical 9]

Spherical fused silica (average particle size 22 μm) 87.0 parts by weight Carnauba wax 0.4 parts by weight Inorganic ion exchanger 0.4 parts by weight γ-glycidoxypropyltrimethoxysilane 0.4 parts by weight Carbon Black 0 0.3 part by weight was mixed at room temperature with a mixer, kneaded with a roll at 70 to 110 ° C., cooled, pulverized, and tableted to obtain an epoxy resin composition. This epoxy resin composition was evaluated by the following methods. The results are shown in Table 1.

Evaluation method-Spiral flow: A mold temperature of 175 was used using a mold for spiral flow measurement according to EMMI-1-66.
The measurement was performed at a temperature of ℃, injection pressure of 6.9 MPa, and curing time of 120 seconds. The unit is cm. -Curing torque: Using a curast meter (JSR curast meter IVPS type manufactured by Orientec Co., Ltd.),
The mold temperature was 175 ° C. and the torque 90 seconds after the start of heating was determined. The torque in the curast meter is a parameter of curability, and the larger the value, the better the curability. The unit is Nm. -Hot bending strength-Hot bending elastic modulus: A low-pressure transfer molding machine is used to mold a test piece at a mold temperature of 175 ° C, 9.8 MPa, and a curing time of 120 seconds, and post-cure at 175 ° C for 8 hours. After that, the bending strength under heat and the bending elastic modulus under heat are measured according to JIS K6911 (at 260 ° C).
It was measured. The unit is N / mm ² . Water absorption rate: using a low-pressure transfer molding machine, mold temperature 175 ° C., 9.8 MPa, curing time 120 seconds, diameter 50
A disc-shaped test piece having a thickness of 3 mm and a thickness of 3 mm was molded and post-cured at 175 ° C. for 8 hours. The change in weight of the test piece before the water absorption treatment and after the moisture absorption treatment in an environment of 85 ° C. and a relative humidity of 85% for 168 hours were measured, and the water absorption rate of the test piece was shown in percentage. Units%. Solder crack resistance: Using a low-pressure transfer molding machine, 160 pLQFP (thickness 1.4 mm, chip size 7 mm × 7 mm) was molded at a mold temperature of 175 ° C., an injection pressure of 9.3 MPa, and a curing time of 120 seconds. As a post cure, 85 packages of 5 packages treated at 175 ° C for 8 hours
After processing for 168 hours in an environment of ℃ and 60% relative humidity,
IR reflow treatment (260 ° C.) was performed. Observe the presence or absence of internal peeling or cracks after treatment with an ultrasonic flaw detector,
Counted the number of defective packages. When the number of defective packages is n, it is displayed as n / 5. -Flame retardancy: A low-pressure transfer molding machine was used to mold a test piece at a mold temperature of 175 ° C, 9.8 MPa, and a curing time of 120 seconds, and post cure was performed at 175 ° C for 8 hours, and then UL-94 vertical. A test (test piece thickness 1.6 mm and 3.2 mm) was performed to determine flame retardancy.

Examples 2 to 8 and Comparative Examples 1 to 11 Epoxy resin compositions were obtained in the same manner as in Example 1 according to the formulations in Tables 1 and 2 and evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2. The materials used in other than Example 1 are shown below. Curing accelerator f represented by formula (7) (hydroxyl group equivalent 224, phosphorus content 3.46% by weight)

[0035]

[Chemical 10]

A curing accelerator g represented by the formula (8) (hydroxyl group equivalent 165, phosphorus content 4.71% by weight)

[0037]

[Chemical 11]

A curing accelerator h represented by the formula (9) (hydroxyl group equivalent 718, phosphorus content 4.31% by weight)

[0039]

[Chemical 12]

A curing accelerator i represented by the formula (10) (hydroxyl group equivalent: 238, phosphorus content: 4.34% by weight)

[0041]

[Chemical 13]

1,8-diazabicyclo (5,4,0) undecene-7 (curing accelerator j) Epoxy resin b containing the formula (11) as a main component (melting point 105 ° C., epoxy equivalent 18)
5, ICI melt viscosity at 150 ℃ 0.2 × 10 ² mPa
・ S)

[0043]

[Chemical 14]

Phenolic resin d represented by the formula (12)
(IC at a softening point of 65 ° C, a hydroxyl equivalent of 168, and 150 ° C
I melt viscosity 0.9 × 10 ² mPa · s)

[0045]

[Chemical 15]

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

INDUSTRIAL APPLICABILITY According to the present invention, an epoxy resin composition for semiconductor encapsulation having excellent moldability is obtained, and a semiconductor device excellent in flame retardancy and solder crack resistance is obtained without using a flame retardant. be able to.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4J002 CC04X CD04W CD05W CD06W                       CD07W CD13W CD20W DE136                       DE146 DJ006 DJ016 EW177                       FD016 FD130 FD14X FD157                       GQ01 GQ05                 4J036 AC01 AC02 AC03 AD01 AD08                       AF01 AF06 DD07 FA01 FA03                       FA05 FB08                 4M109 AA01 EA02 EB04 EB12

Claims (2)

[Claims] 1. An epoxy resin represented by the general formula (1) (A), a phenol resin represented by the general formula (2) (B),
(C) an inorganic filler and (D) a phosphorus-containing curing accelerator represented by the general formula (3) as an essential component, and the inorganic filler in the total epoxy resin composition is 80 to 90% by weight, and the total epoxy is An epoxy resin composition for semiconductor encapsulation, wherein the phosphorus content in the resin composition due to the curing accelerator containing phosphorus is 0.015 to 0.05% by weight. [Chemical 1] (In the formula, R ₁ and R ₂ are groups selected from alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is An integer of 0 to 4, and n is a positive number of 1 to 5 on average. [Chemical 2] (In the formula, R ₁ and R ₂ are groups selected from alkyl groups having 1 to 4 carbon atoms and may be the same or different. A is an integer of 0 to 3 and b is An integer of 0 to 4, and n is a positive number of 1 to 5 on average. [Chemical 3] (In the formula, R _{1 to} R ₄ each represent a substituent selected from the group consisting of a monovalent aromatic ring-containing organic group and a monovalent aliphatic residue, and may be the same or different. Well, the organic acid Y ^n- [H ⁺ ] _nm represents an organic anion that releases m protons out of the molecule, n ≧ m ≧ 1). 2. A semiconductor device obtained by encapsulating a semiconductor element using the epoxy resin composition according to claim 1.